Plasma display panel

ABSTRACT

A plasma display panel includes a first substrate and a second substrate facing each other to provide a discharge space between the first substrate and the second substrate, a scan electrode and a sustain electrode both provided on the first substrate, a dielectric layer for covering the scan electrode and the sustain electrode, and a protective layer provided on the dielectric layer. The protective layer includes magnesium oxide, magnesium carbide, and silicon. This plasma display panel performs stable discharge characteristics, such as a driving voltage, thereby displaying an image stably.

TECHNICAL FIELD

The present invention relates to a plasma display panel for displayingan image.

BACKGROUND OF THE INVENTION

Various types of display devices, such as a cathode ray tube (CRT), aliquid crystal display (LCD), and a plasma display panel (PDP), whichare to be used for a high-definition and large display television, havebeen developed.

The PDP includes phosphor layers for emitting three primary colors, red(R), green (G), and blue (B) so as to perform full color display byadding and mixing three primary colors (red, green, and blue). The PDPhas a discharge cell, and generates visible light by exciting phosphorlayers with ultraviolet rays generated by a discharge in the dischargecell, thereby displaying an image.

In an AC type PDP, an electrode for main discharge is generally coveredwith a dielectric layer, and performs memory driving to reduce a drivingvoltage. When the dielectric layer deteriorates due to an impact of ionsgenerated by the discharge and hitting the layer, the driving voltagemay increase. To prevent this increasing, a protective layer forprotecting the dielectric layer is formed on a surface of the dielectriclayer. For example, a protective layer made of material having highsputtering resistance, such as magnesium oxide (MgO), is disclosed inpp. 79-80 in “ALL ABOUT PLASMA DISPLAY” co-authored by Hiraki Uchiikeand Shigeo Mikoshiba, published by Kogyo Chosakai Publishing Inc. inMay, 1, 1997.

The conventional PDP structured may provide the following problem. Inthe PDP, a pulse of a driving voltage is applied to the electrodes forgenerating a discharge in the discharge cell. This discharge may delayfrom the rising of the pulse by a period of time, “a discharge delaytime”. This discharge delay time may decrease a probability of end ofthe discharge depending on driving conditions while the pulse isapplied. As a result, an electric charge may not be stored in adischarge cell to illuminate actually, thereby causing illuminationfailure and having quality deteriorate.

SUMMARY OF THE INVENTION

A plasma display panel includes a first substrate and a second substratefacing each other to provide a discharge space between the firstsubstrate and the second substrate, a scan electrode and a sustainelectrode both provided on the first substrate, a dielectric layer forcovering the scan electrode and the sustain electrode, and a protectivelayer provided on the dielectric layer. The protective layer includesmagnesium oxide, magnesium carbide, and silicon.

This plasma display panel performs stable discharge characteristics,such as a driving voltage, thereby displaying an image stably.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially-sectional, perspective view of a plasma displaypanel (PDP) in accordance with an exemplary embodiment of the presentinvention.

FIG. 2 is a sectional view of the PDP in accordance with the embodiment.

FIG. 3 is a block diagram of an image display using the PDP inaccordance with the embodiment.

FIG. 4 is a timing chart of a driving waveform of the image displayshown in FIG. 3.

FIG. 5 shows an evaluated result of the PDP in accordance with theembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a partially-sectional, perspective view of an ACsurface-discharge type plasma display panel (PDP) 101 for schematicallyillustrating a structure of the PDP. FIG. 2 is a sectional view of PDP101.

In front panel 1, a pair of stripe scan electrode 3 and stripe sustainelectrode 4 forms a display electrode. Plural pairs of scan electrode 3and sustain electrode 4, i.e. plural of display electrodes, are providedon surface 2A of front glass substrate 2. Dielectric layer 5 covers scanelectrode 3 and sustain electrode 4 is formed, and protective layer 6for covering dielectric layer 5 is formed.

In rear panel 7, stripe address electrode 9 is provided on surface 8A ofrear glass substrate 8 perpendicularly to scan electrode 3 and sustainelectrode 4. Electrode protective layer 10 covering address electrode 9protects address electrode 9, and reflects visible light in a directiontowards front panel 1. Barrier ribs 11 are provided on electrodeprotective layer 10 and extend in the same direction as addresselectrode 9 and sandwich address electrode 9. Phosphor layer 12 isformed between barrier ribs 11.

Front glass substrate 2 faces rear glass substrate 8 to form dischargespace 13 between the substrates. Discharge space 13 is filled withdischarge gas, such as mixture rare gas of neon (Ne) and xenon (Xe), andsealed at a pressure of approximately 66500 Pa (500 Torr). Thus, anintersection between address electrode 9 and both of scan electrode 3and sustain electrode 4 is separated by barrier ribs 11 to function asdischarge cell 14, a unit emitting region. Rear glass substrate 8 isarranged apart from protective layer 6 by a predetermined distance toprovide discharge space 13 between protective layer 6 and rear glasssubstrate 8.

In PDP 101, a driving voltage is applied to address electrode 9, scanelectrode 3, and sustain electrode 4, so that discharge is generated atdischarge cell 14. An ultraviolet ray generated by this dischargeirradiates phosphor layer 12, and is converted into visible light todisplay an image.

FIG. 3 is a block diagram of an image display including PDP 101 and adriving circuit for driving PDP 101 for schematically illustrating thedisplay. Address-electrode driver 21 is connected to address electrode 9of PDP 101, scan-electrode driver 22 is connected to scan electrode 3,and sustain-electrode driver 23 is connected to sustain electrode 4.

In order to drive the image display using the AC surface-discharge typePDP 101, a single frame of an image is divided into plural subfields todisplay gradation on PDP 101. In this method, each subfield is furtherdivided into four periods to control the discharge at discharge cell 14.FIG. 4 is a timing chart of a driving waveform in each subfield.

The timing chart of FIG. 4 shows the driving waveform of the imagedisplay shown in FIG. 3, and shows a voltage waveform applied toelectrodes 3, 4 and 9 in each subfield. In setting-up period 31,initializing pulse 51 is applied to scan electrode 3 to cause alldischarge cells 14 of PDP 101 to store wall electric charges forfacilitating the discharge. In addressing period 32, data pulse 52 andscanning pulse 53 are applied to address electrode 9 and the scanelectrode, respectively, which correspond to discharge cell 14 toilluminate. Thus, the discharge to cause discharge cell 14 to illuminateis generated. In sustaining period 33, sustain pulses 54 and 55 areapplied to all scan electrodes 3 and sustain electrodes 4, respectively,so that discharge cell 14 having the discharge generated therein inaddressing period 32 illuminates, and then the illumination issustained. In erasing period 34, erasing pulse 56 is applied to sustainelectrode 4, so that the wall electric charge stored in discharge cell14 is erased to stop the illumination of discharge cell 14.

In setting-up period 31, initializing pulse 51 is applied to scanelectrode 3, so that scan electrode 3 has an electric potential higherthan potentials of both address electrode 9 and sustain electrode 4 togenerate the discharge at each discharge cell 14. Electric chargegenerated by the discharge is stored on a wall of each discharge cell 14so as to cancel a difference between the potential of address electrode9 and the potential of each of scan electrode 3 and sustain electrode 4.Then, a negative electric charge as a wall electric charge is stored ona surface of protective layer 6 near scan electrode 3. A positiveelectric charge as a wall electric charge is stored on a surface ofphosphor layer 12 near address electrode 9 and on a surface ofprotective layer 6 near sustain electrode 4. These wall electric chargesprovides a predetermined wall electric potential between scan electrode3 and address electrode 9, and provides a predetermined wall electricpotential between scan electrode 3 and sustain electrode 4.

In addressing period 32, scan pulses 53 are sequentially applied to scanelectrodes 3, so that scan electrodes 3 have electric potentials lowerthan a potential of sustain electrode 4, and data pulse 52 is applied toaddress electrode 9 corresponding to discharge cell 14 to illuminate. Atthis moment, address electrode 9 has an electric potential higher thanthat of scan electrodes 3. That is, a voltage is applied between scanelectrode 3 and address electrode 9 in the same polarity as the wallelectric potential, and a voltage is applied between scan electrode 3and sustain electrode 4 in the same polarity as the wall electricpotential. These voltages generate a writing discharge at discharge cell14. As a result, a negative electric charge is stored on a surface ofphosphor layer 12 and a surface of protective layer 6 near sustainelectrode 4, and a positive electric charge is stored on a surface ofprotective layer 6 near scan electrode 3. Thus, a predetermined wallelectric potential is generated between sustain electrode 4 and scanelectrode 3.

The writing discharge delayed by a discharge delay time after scan pulse53 and data pulse 52 are applied to scan electrodes 3 and addresselectrode 9, respectively. If the discharge delay time is long, thewriting discharge may not be generated in a period (addressing period)during which scan pulse 53 and data pulse 52 are applied to scanelectrodes 3 and address electrode 9, respectively. At discharge cell 14in which the writing discharge is not generated, even when sustainpulses 54 and 55 are applied to scan electrodes 3 and sustain electrode4, the discharge is not generated, and phosphor layer 12 does not emitlight, thus adversely affecting the image display. PDP 101, performinghigh resolution display, the addressing period assigned to scanelectrode 3 becomes short, so that a probability that writing dischargeis not generated becomes high. Furthermore, if the partial pressure ofXe in the discharge gas is not lower than 5%, the probability that thewriting discharge is not generated becomes high. In addition, if barrierribs 11 are not formed as stripe patterns shown in FIG. 1 but as a meshpattern surrounding discharge cell 14, the probability that the writingdischarge is not generated becomes high even in the case that a lot ofthe impurity gases remains.

In sustaining period 33, sustain pulse 54 is applied to scan electrodes3 so that scan electrode 3 has an electric potential higher than that ofsustain electrode 4. That is, a voltage is applied between sustainelectrode 4 and scan electrode 3 in the same polarity as the wallelectric potential generate a sustain discharge. As a result, dischargecell 14 can start illuminating. Sustain pulses 54 and 55 are applied tochange respective polarities of sustain electrode 4 and scan electrode 3alternately, thereby generating pulse emission intermittently indischarge cell 14.

In erasing period 34, narrow erasing pulse 56 is applied to sustainelectrode 4 generate an insufficient discharge, thereby erasing the wallelectric charge.

Protective layer 6 of PDP 101 of the embodiment will be described below.

Protective layer 6 is made of magnesium oxide (MgO) including silicon(Si) and magnesium carbide, such as MgC₂, Mg₂C₃, and Mg₃C₄. Protectivelayer 6 is formed by providing an evaporation source including MgO,silicon, and magnesium carbide, such as MgC₂, Mg₂C₃, Mg₃C₄, heating theevaporation source is heated by a heating device, such as a Pierce typeelectron beam gun, in oxygen atmosphere, and depositing the heatedsource on dielectric layer 5.

PDP 101 includes protective layer 6 discussed above. Protective layer 6prevents an error that a writing discharge is not generated sinceshortening a discharge delay time in addressing period 32 for thefollowing reason.

A conventional protective layer includes highly-pure, about 99.99% ofMgO provided by a vacuum evaporation method (EB method), hence having asmall electronegativity and a large ionicity. Therefore, Mg ion at asurface of the protective layer is unstable (in a high-energy state),hence adsorbing hydroxyl group (OH group) to be stable. (For example,see “COLOR MATERIAL” 69(9), 1996, pp. 623-631.) According to cathodeluminescence analysis, it is confirmed that peaks of cathodeluminescence caused by a lot of oxygen defects appears. The conventionalprotective layer has a lot of defects which adsorb impurity gas, such asH₂O, CO₂, and hydrocarbon (CHx). (For example, see documents ofDischarge Research Institute at Institute of Electrical Engineers ofJapan EP-98-202, 1988, p. 21).

A main cause of the delay of the discharge delaying may be that aprimary electron serving as a trigger for starting the discharge ishardly emit from the protective layer to the discharge space.

Magnesium carbide, such as MgC₂, Mg₂C₃, or Mg₃C₄, and silicon is addedto protective layer 6 of MgO. This addition changes a distribution ofoxygen defects in MgO crystal, thereby preventing the discharge delayand writing errors.

In a process for forming protective layer 6, conditions, such as thevalue of an electron beam current, a partial pressure of oxygen, atemperature of substrate 2, do not affect the composition of protectivelayer 6 much, hence being determined arbitrarily. For example, a vacuumdegree may be set to a value not higher than 5.0×10⁻⁴ Pa, thetemperature of substrate 2 may be set to a value not lower than 200° C.,and a pressure for vapor deposition may be set to a value ranging from3.0×10⁻² Pa to 8.0×10⁻² Pa.

A method of forming protective layer 6 is not limited to the vapordeposition mentioned above, but may be employ a sputtering method or anion plating method. The sputtering method would employ a target formedby sintering MgO powder in air, and the target may include silicon andmagnesium carbide, such as MgC₂, Mg₂C₃, or Mg₃C₄. The ion plating methodwould employ the evaporation source mentioned above for the vapordeposition method.

MgO, the magnesium carbide, such as MgC₂, Mg₂C₃, or Mg₃C₄, and siliconare not necessarily mixed previously as materials. Protective layer 6may be formed by preparing separate targets or evaporation sources andthen mixing the materials evaporated.

Next, a method of manufacturing PDP 101 of the embodiment will bedescribed below. First, a method of manufacturing front panel 1 will bedescribed.

Scan electrode 3 and sustain electrode 4 are formed on front glasssubstrate 2, and covered with lead-base dielectric layer 5. Protectivelayer 6 including MgO, silicon, and the magnesium carbide, such as MgC₂,Mg₂C₃, or Mg₃C₄ is formed on a surface of dielectric layer 5, thusproviding front panel 1.

In PDP 101 according to the embodiment, each of scan electrode 3 andsustain electrode 4 may include a transparent electrode and a silverelectrode as a bus electrode formed on the transparent electrode. Thetransparent electrode is formed to have a stripe shape by aphotolithography method, and the silver electrode is formed on thetransparent electrode by a photolithography method. Then, theseelectrodes are baked.

Lead-based dielectric layer 5 has its composition of, for example, 75wt. % of lead oxide (PbO), 15 wt. % of boron oxide (B₂O₃), and 10 wt. %of silicon oxide (SiO₂). Dielectric layer 5 is formed by, for example,screen printing and baking.

Protective layer 6 is formed by the vacuum deposition method, thesputtering method, or the ion plating method.

In order to form protective layer 6 by the sputtering method, the targetincluding MgO and additive including 40 ppm by weight to 7000 ppm byweight of magnesium carbide, such as MgC₂, Mg₂C₃, or Mg₃C₄, and 20 ppmby weight to 7500 ppm by weight of silicon is sputtered in sputteringgas, such as Ar gas, and reaction gas, such as oxygen gas (O₂ gas),thereby providing protective layer 6. In this sputtering, while frontglass substrate 2 is heated at a predetermined temperature (200° C.-400°C.), Ar gas and O₂ gas (if necessary) is put into a sputtering apparatusdepressurized within a range from 0.1 Pa to 10 Pa by an exhaustingapparatus, thereby providing protective layer 6. In order to facilitateadding the additive, simultaneously to the sputtering, while an electricpotential ranging from −100V to 150V is applied to front glass substrate2 by a bias supply, the target is sputtered to form protective layer 6.This process further improves its characteristics. The amount of theadditive to be put into MgO is controlled by the amount of the additivein the target and a high-frequency electric power for generatingdischarge for the sputtering.

In the case that protective layer 6 is formed by the vacuum depositionmethod, front glass substrate 2 is heated at 200° C.-400° C., and adeposition chamber is depressurized at 3×10⁻⁴ Pa by an exhaustingapparatus. A predetermined number of evaporation sources of hollowcathodes and an electron beam is set in the chamber as to evaporate MgOand the additive added to MgO. Then, these materials are deposited onprotective layer 6 with using reaction gas, such as oxygen gas (O₂ gas).According to the embodiment, while O₂ gas is put into the depositionchamber depressurized within a range from 0.01 Pa to 1.0 Pa by theexhausting system. Then, MgO and the additive, i.e., 40 ppm by weight to7000 ppm of magnesium carbide, such as MgC₂, Mg₂C₃, or Mg₃C₄, and 20 ppmby weight to 7500 ppm by weight of silicon are evaporated by theelectron beam or the evaporation source of the hollow cathode, therebyproviding protective layer 6 on dielectric layer 5.

Next, a method of manufacturing rear panel 7 will be described below.

Silver-based paste is applied on rear glass substrate 8 by screenprinting and then is baked to provide address electrode 9. Lead-baseddielectric layer 18 for protecting the electrode is formed on addresselectrode 9 by screen printing, and is baked similarly to front panel 1.Barrier ribs 11 made of glass are provided at predetermined pitches andfixed. One of red phosphor, green phosphor and blue phosphor is providedin a space surrounded by barrier ribs 11, thus providing phosphor layer12. In the case that barrier ribs are provided to form a mesh patternsurrounding discharge cell 14, another barrier rib is formedperpendicularly to barrier rib 11 shown in FIG. 1.

The phosphors in above may employ phosphors generally in PDPs, such as:

-   -   Red phosphor: (Y_(X)Gd_(1-X))BO₃:Eu    -   Green phosphor: Zn₂SiO₄:Mn, (Y, Gd)BO₃:Tb    -   Blue phosphor: BaMgAl₁₀O₁₇:Eu

Front panel 1 and rear panel 7 manufactured by the above mothod arebonded with each other with sealing glass so that scan electrode 3 andsustain electrode 4 face address electrode 9 perpendicularly to addresselectrode 9. Then, discharge space 13 partitioned by barrier ribs 11 isexhausted to high vacuum (e.g. 3×10⁻⁴ Pa) as exhausting baking. Then,the discharge gas having a predetermined composition is put intodischarge space 13 at a predetermined pressure, hence providing PDP 101.

PDP 101, being used for 40-inch class hi-definition TV, has dischargecells 14 having small sizes and arranged by a small pitch, andtherefore, may preferably includes the barrier ribs arranged in the meshpattern to increase brightness.

The composition of the filling discharge gas may be of Ne—Xe-based. Thepartial pressure of Xe may be preferably determined to be not lower than5%, and the pressure of the discharge gas may be preferably determinedto be within 450-760 Torr to increase a brightness of the dischargecell.

Samples of the PDP manufactured by the above method were prepared andevaluated for evaluating performance of the PDP according to the presentembodiment.

Plural kinds of evaporation sources, i.e., materials of protective layer6 including magnesium carbide, such as MgC₂, having its concentrationranging from 0 ppm by weight to 7000 ppm by weight and silicon havingits concentration ranging from 0 ppm by weight to 7500 ppm by weightboth added to MgO were prepared. Plural kinds of front panels includingthe protective layers formed by using these evaporation sources weremanufactured. Then, samples of the PDP were prepared by using thesematerials. The samples of the PDP were measured in discharge delay timeunder atmospheric temperatures ranging from −5° C. to 80° C. Accordingto results of this measurement, an Arrhenius plot of the discharge delaytime to the temperatures was produced, and then, activation energy inthe discharge delay time was obtained from an approximate straight lineof the plot. Discharge gas filling in the sample is mixture gas ofNe—Xe, and the partial pressure of Xe was 5%.

The discharge delaying time here is a period of time from the time avoltage is applied between scan electrode 3 and address electrode 9 tothe time the discharge (writing discharge) occurs. The time illuminationcaused by the writing discharge exhibits a peak is regarded as the timewhen the writing discharge occurs. A period of time from the time apulse is applied to an electrode of each sample till the time when thewriting discharge occurs was measured 100 times and averaged, thusproviding the discharge delay time.

The activation energy is a value showing characteristics, such as avariation of the discharge delay time against temperatures. It isconsidered that the lower the value of activation energy is, the lessthe characteristics change against the temperatures.

FIG. 5 shows the concentrations of silicon and magnesium carbide bothadded to the evaporation source of MgO as material of protective layer6, the activation energy of the samples of the PDP including protectivelayer 6 formed by using the evaporation sources, and a status ofillumination (whether flicker was observed or not) of the samples of thePDP. Regarding the flicker, “visible” shown in FIG. 5 represents thecase that the flicker is visible when the samples of the PDP operateswhile changing an atmospheric temperature from −5° C. to 80° C. In FIG.5, activation energy of a sample (sample No. 21) of a conventional panelhaving a protective layer by using the evaporation source including madeof MgO with no additive is expressed as “1”, and activation energy ofeach sample is expressed as a value relative to the sample of theconventional panel.

Each sample including the concentration of magnesium carbide in theevaporation source of MgO larger than 7000 ppm by weight and theconcentration of silicon larger than 7500 ppm by weight exhibited a longdischarge delay time, or required an extremely-high voltage to producethe discharge, thereby not being able to display an image with aconventional voltage. Samples Nos. 1-20 have activation energy smallerthan activation energy of the conventional sample, however, samples Nos.16-20 exhibited flickers. As shown in FIG. 5, the flicker did not occurin each sample provided by using the evaporation source of MgO including40 ppm by weight to 7000 ppm by weight of magnesium carbide and 20 ppmby weight to 7500 ppm by weight of silicon. Protective layer 6 includingsilicon has electron-emission ability better than that of theconventional sample.

A high partial pressure of Xe in the discharge gas tends to increase avariation of the discharge delay time against a temperature, thuscausing the temperature to affect operating and displayingcharacteristics of the PDP. For this reason, a small activation energyshown in FIG. 5 is preferable. Relative values of the activation energyof samples Nos. 1-15 are extremely low. For this reason, even if theNe—Xe discharge gas includes a high partial pressure, 10%-50%, of Xe,samples including protective layer 6 formed by using the evaporationsource of MgO including 40 ppm by weight to 7000 ppm by weight ofmagnesium carbide and 20 ppm by weight to 7500 ppm by weight of siliconhad small flicker due to temperature characteristics of the dischargedelay time, thus preferably displaying images.

Protective layer 6 formed by using the evaporation source of MgOincluding 40 ppm by weight to 7000 ppm by weight of magnesium carbideand 20 ppm by weight to 7500 ppm by weight of silicon is made ofmagnesium oxide including 40 ppm by weight to 7000 ppm by weight ofmagnesium carbide and 20 ppm by weight to 7500 ppm by weight of silicon.Even if the partial pressure of Xe in the discharge gas is not lowerthan 10%, the samples of the PDP including protective layer 6 displayimages without changing voltages applied to electrodes from conventionalvoltage values, and reduce a variation of the discharge delay timeagainst temperature.

It is considered that the additive of magnesium carbide, such as MgC₂ orMg₂C₃, and silicon (Si) added into magnesium oxide (MgO) changes theconcentration or distribution of oxygen defects in crystals of MgO.Thereby, factors increasing variation of characteristics againsttemperature are eliminated, thus reducing the variation ofcharacteristics against temperature.

The protective layer made of MgO, magnesium carbide, and Si, shortensthe discharge delay time, and accordingly reduces a variation of thedischarge delay time against temperature. Thus, the protective layer hasexcellent electron emission ability hardly changing against temperature.This allows PDP 101 according to the embodiment to preferably displayimages regardless of environmental temperature.

According to the embodiment, the magnesium carbide is MgC₂, Mg₂C₃, orMg₃C₄, and may be mixture of, for example, MgC₂ and Mg₂C₃. That is, theprotective layer may include at least one of MgC₂, Mg₂C₃, and Mg₃C₄ asthe magnesium carbide. In this case, the total amount of the magnesiumcarbide ranges from 40 ppm by weight to 7000 ppm by weight, providingthe same effect.

INDUSTRIAL APPLICABILITY

A plasma display panel of the present invention has stable dischargecharacteristics, such as a driving voltage, and displays an imagestably.

1. A plasma display panel comprising: a first substrate and a secondsubstrate facing each other to provide a discharge space between thefirst substrate and the second substrate; a scan electrode and a sustainelectrode both provided on the first substrate; a dielectric layer forcovering the scan electrode and the sustain electrode; and a protectivelayer provided on the dielectric layer, the protective layer includingmagnesium oxide, magnesium carbide, and silicon.
 2. The plasma displaypanel of claim 1, wherein the protective layer includes 40 ppm by weightto 7000 ppm by weight of magnesium carbide and 20 ppm by weight to 7500ppm by weight of silicon.
 3. The plasma display panel of claim 1,wherein the magnesium carbide of the protective layer comprises at leastone of MgC₂, Mg₂C₃ and Mg₃C₄.
 4. A method of manufacturing a plasmadisplay panel, comprising: forming a scan electrode and a sustainelectrode on a first substrate; forming a dielectric layer for coveringthe scan electrode and the sustain electrode; forming a protective layeron the dielectric layer by using material including magnesium oxide,magnesium carbide, and silicon; and providing a second substrate apartfrom the protective layer by a predetermined distance so as to provide adischarge space between the protective layer and the second substrate.5. The method of claim 4, wherein the material of the protective layerincludes 40 ppm by weight to 7000 ppm by weight of magnesium carbide and20 ppm by weight to 7500 ppm by weight of silicon.
 6. The method ofclaim 4, wherein the magnesium carbide of the material of the protectivelayer comprises at least one of MgC₂, Mg₂C₃, and Mg₃C₄.
 7. A materialused for a method of manufacturing a plasma display panel, the materialcomprising magnesium oxide, magnesium carbide, and silicon, wherein themethod comprises: forming a scan electrode and a sustain electrode on afirst substrate; forming a dielectric layer for covering the scanelectrode and the sustain electrode; forming a protective layer on thedielectric layer by using the material; and providing a second substrateapart from the protective layer by a predetermined distance to provide adischarge space between the protective layer and the second substrate.8. The material of claim 7, comprising 40 ppm by weight to 7000 ppm byweight of the magnesium carbide and 20 ppm by weight to 7500 ppm byweight of the silicon.
 9. The material of claim 7, wherein the magnesiumcarbide comprises at least one of MgC₂, Mg₂C₃ and Mg₃C₄.